Lymphatic System

WARM UP:  Get a note sheet from the front stool.  We will finish Ch. 16 today.  Next class we will review Ch. 16.  On Thursday the 12 th, you will have a test on Ch. 14, 15, & 16!

Lymphatic System  A part of the immune system  Helps destroy microorganisms that enter the body  Works closely with the circulatory system  Both systems move liquids through the body  Both systems contain white blood cells

Functions of the Lymphatic System: 1. It absorbs some of the tissue fluid that collects around cells. 2. It absorbs fats from the digestive system and transports them to the circulatory system. 3. It filters dead cells, viruses, bacteria, and other unneeded particles from tissue fluid and then returns the tissue fluid to the circulatory system. 4. It helps fight off illness and infections and includes structures in which white blood cells develop.

Parts of the Lymphatic System:  Lymph  Lymph vessels  Lymph nodes  Bone marrow  Thymus  Spleen  Tonsils

Lymph:  Water, white blood cells, and dissolved materials like salts and glucose leak out of capillary walls and into the spaces around tissue cells = tissue fluid  Cells absorb the materials they need from tissue fluid and release waste into it  About 90% of the tissue fluid is reabsorbed by the capillaries.  About 10% of the tissue fluid is absorbed by the lymph vessels = lymph

Lymph Vessels:  The lymphatic system forms a network of lymph vessels that look similar to the circulatory system’s network of blood vessels.  Lymph vessels absorb and transport lymph.  Lymph is pushed through the lymph vessels by contractions of the muscles you use to move your body (NOT THE HEART!)

Lymph Nodes:  Lymph vessels include clusters of small, spongy structures that filters particles from lymph = lymph nodes  Bacteria, viruses, fungi, and pieces of dead cells are trapped and removed from the lymph as it flows through a lymph node  Lymph nodes also store white blood cells that attack and destroy the trapped particles

Lymph Nodes (cont.):  Large groups of lymph nodes are in the neck, the groin, and the armpits  When you have in infection, your body increases its production of white blood cells that fight the infection  Many of these white blood cells gather in your lymph nodes and cause the nodes to swell  The swelling disappears when the infection is gone.

Bone Marrow:  Lymphocytes are white blood cells that destroy pathogens- infection- causing microorganisms such as viruses and bacteria  Bone marrow is the spongy center of bones where red and white blood cells form  Lymphocytes include B cells and T cells  B cells mature in the bone marrow  T cells mature in the thymus gland

Thymus:  The thymus is the organ of the lymphatic system in which T cells complete their development  After immature T cells move from the bone marrow to the thymus, they develop the ability to recognize and destroy body cells that have been infected  Mature B cells and T cells move into the lymph and blood to help fight infection

Spleen:  The spleen is an organ of the lymphatic system that recycles worn-out red blood cells and produces and stores lymphocytes  The spleen also stores blood and platelets  If a person is injured and loses a lot of blood, the spleen can release stored blood and platelets in the circulatory system

Tonsils:  Tonsils are clusters of lymph tissue on the sides of your throat  They help protect your body from infection by trapping and destroying bacteria and other pathogens that enter your nose and mouth  But…you can live without your tonsils.

Lymphatic System & Homeostasis:  The lymphatic system helps maintain your body’s homeostasis by regulating fluid buildup around cells.  It supports the circulatory system by cleaning fluids and replacing them in the bloodstream.  It also supports overall health by helping fight infection throughout the body.

 oduct.html oduct.html  Brain Pop- Lymphatic System

NOTEBOOK:  Blood Vessels- Article & Questions  Blood Fill-in-the-Blank  Title Page  Lymphatic System  Lymphatic System Notes  Lymphatic System BrainPop Quiz  Title Page  Ch. 16 Review  Cardiovascular Health  Circulatory System- Article & Questions  Respiratory System Article  Review- The Respiratory System